1. Bring 6 cups water to a boil in a large pot. Add noodles, then remove from heat and let stand, stirring occasionally, until just tender, 7 to 9 min. Drain well. Meanwhile, in a small bowl, whisk coconut milk with lime zest and juice, brown sugar, fish sauce and hot pepper flakes.

2. Heat a large non-stick frying pan over medium-high. Add oil, then onion. Cook until almost softened, 3 min. Add shrimp and cook until it turns pink, 2 to 3 min. Add snow peas, coconut milk mixture and noodles. Cook until noodles are heated through, 1 to 2 min. Remove from heat and stir in basil.